This is an exceptional example of a U.S. Springfield Armory Second Model Allin Conversion rifle as produced circa 1866. There were 25,000 produced at Springfield. These rifles were the transition from using a Civil War muzzle loader to true breech loaders. The casehardened lock plate is dated "1864" behind the hammer and is marked with the eagle and shield followed by "U.S./SPRINGFIELD" in two lines ahead of it. The top of the breechblock is stamped "1866" above an eagle head. There is a "C" stamped on the left side of the barrel below the breechblock. The buttplate is marked "US" on the top tang and all three barrel bands are marked with the letter "U". There is a fixed front sight and a two leaf, fold down rear sight. The stock is marked with a boxed "HSB" script cartouche on the left side and an "L" behind the lower trigger guard tang. The barrel and furniture have the standard Springfield "National Armory Bright" finish. The hammer and lock plate have a color casehardened finish and the breechblock has a black, oil-quenched finish. With a cleaning rod.